Put latest_rev data in datastore instead of memcache.

app.py

Index: app.py
diff --git a/app.py b/app.py
index 0a5519163f8a4bad86f0c17fd8b9c51b535e4fee..aeab307fc29b3cee9365583e25f797acef7e25b3 100644
--- a/app.py
+++ b/app.py
@@ -212,7 +212,7 @@ def get_and_cache_rowdata(localpath):
   Here we assume localpath is already unquoted.
   """
   row_data = get_data_from_cache(localpath)
-  if row_data:
+  if row_data and type(row_data) == type({}):

[Ryan Tseng, 2013/01/15 22:05:32]

In what cases would it not be a dict?

[agable, 2013/01/15 22:09:41]

The latest_rev row used to be stored in memcache as a plain int. I want to make
sure it never picks up that int and tries to use it instead.

     return row_data
   row = Row.all().filter('localpath =', localpath).get()

[Ryan Tseng, 2013/01/15 22:05:32]

How many entires can we expect this to return?

[agable, 2013/01/15 22:09:41]

Exactly one. It is being replaced by row = Row.get_by_key_name(localpath) in a
different CL.

   if not row:
@@ -254,11 +254,21 @@ def save_row(row_data, localpath):
     # pylint: disable=E1103
     row.put()
   db.run_in_transaction(tx_row, row_key)
-  prev_rev = memcache.get(key='latest_rev')
-  if (rev_number > prev_rev):
-    memcache.set(key='latest_rev', value=rev_number)
   put_data_into_cache(localpath, row_data)
   logging.info('Saved and cached row with localpath %s' % localpath)
+  # Update latest_rev in datastore & cache, or create it if it doesn't exist.
+  prev_rev = get_and_cache_rowdata('latest_rev')
+  if not prev_rev or rev_number > prev_rev['rev_number']:
+    latest_rev_row = {
+        'rev_number': rev_number,
+        'fetch_timestamp': datetime.datetime.now(),
+        'rev': None,
+        'name': None,
+        'status': None,
+        'comment': None,
+        'details': None,
+    }
+    save_row(latest_rev_row, 'latest_rev')
 
 
 ##########
@@ -388,7 +398,7 @@ def console_merger(localpath, remoteurl, page_data,
   surroundings = get_and_cache_pagedata('surroundings')
   merged_page = BeautifulSoup(surroundings['content'])
   merged_tag = merged_page.find('table', 'ConsoleData')
-  latest_rev = int(memcache.get(key='latest_rev'))
+  latest_rev = int(get_and_cache_rowdata('latest_rev')['rev_number'])
   if not latest_rev:
     logging.error('console_merger(\'%s\', \'%s\', \'%s\'): cannot get latest '
                   'revision number.' % (